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TECHNICAL  BULLETIN  No.  23 


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Hybridization  of  Hitis 
Rotundifolia 


Inheritance  of  Anatomical  Stem 

Characteristics 


C.  F.  WILLIAMS,  Asst . 
Division  of  Horticulture 


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JUNE  1923 


TECHNICAL  BULLETIN  No.  23 


Hybridization  of  Vitis  Rotundifolia 

Inheritance  of 
Anatomical  Stem  Characters 


C.  F.  WILLIAMS,  Asst. 
Division  of  Horticulture 


NORTH  CAROLINA  AGRICULTURAL  EXPERIMENT  STATION 

Conducted  Jointly  l>y  the 
STATE  DEPARTMENT  OF  AGRICULTURE 
and  the 

NORTH  CAROLINA  STATE  COLLEGE  OF  AGRICULTURE  AND  ENGINEERING 

RALEIGH 


BULLETINS  OF  THE  STATION  WILL  BE  SENT  FREE  TO  CITIZENS  OF  THE  STATE 


CONTENTS 


Introduction  _ . - ' 

Vitis  rotundifolia _ _ _  _ _ 

Vitis  vinifera  _ _ 

Hybrids  (V.  vinifera  x  V.  rotundifolia)  _ _ 

Vitis  bourquiniana _ 

Hybrids  (V.  bourquiniana  x  V.  rotundifolia)  _ 

Variety  Wincliell  (hybrid  of  V.  labrusca  x  V.  aestivalis  x  V.  vinifera)  __ 

Hybrids  (Var.  Wincliell  x  V.  rotundifolia)  _ 

Hybrids  [  (Wincliell  x  V.  rotundifolia)  x  V.  rotundifolia]  _ 

Discussion  _ 

Summary _ _ 


Page 

o 

_  o 

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__  15 


ILLUSTRATIONS 


Fig.  1. 
Fig.  2. 
Fig.  3. 
Fig.  4. 


(/;)  phellogen,  (/) 
(c)  cambium.  ( r ) 


(Grouped  at  back  of  this  Bulletin) 

Vitis  rotundifolia.  longitudinal  section  through  the  node. 

Vitis  vinifera,  longitudinal  section  through  the  node. 

Vitis  rotundifolia,  transverse  section  of  internode. 

Vitis  rotundifolia,  transverse  section  of  bundle,  ( p )  phellogen.  (/) 
sclerenchyma  fibers,  (/()  hard  bast,  (s)  soft  bast,  (c)  cambium,  (r) 
ray,  (v)  vessel. 

Fig.  5.  Vitis  vinifera.  transverse  section  of  internode. 

Fig.  6.  Vitis  vinifera,  transverse  section  of  bundle, 
sclerenchyma  fibers,  (h)  hard  bast,  ( s )  soft  bast, 
ray,  (v)  vessel. 

Fig.  7.  Hybrid  (V.  viniferox  V.  rotundifolia),  transverse  section  of  bundle. 

Fig.  S.  Hybrid  (V.  vinifera  x  V.  rotundifolia)1,  transverse  section  of  bundle. 

Fig.  9.  Hybrid  (V.  vinifera  x  V.  rotundifolia),  transverse  section  of  bundle. 

Fig.  10.  Hybrid  (V.  vinifera  x  V.  rotundifolia),  transverse  section  of  bundle. 

Fig.  11-44.  Carema  lucida  diagrams  of  transverse  sections  of  bundles,  Fig. 
11.  V.  vinifera,  Fig.  12.  V.  rotundifolia,  Figs.  13-38.  Hybrids  V.  vinifera 
x  V.  rotundifolia.  Figs.  39-44.  Hybrids  bourquiniana  x  V.  rotundifolia, 
(/)  sclerenchyma  bundle,  (p)  phellogen,  (h)  hard  bast,  ( s )  soft  bast, 
(c)  cambium,  (r)  ray,  (v)  vessel. 

Fig.  45.  V.  bourquiniana,  transverse  section  of  bundles. 

Fig.  46.  Variety  Wincliell,  transverse  section  of  internode. 

Fig.  47.  Variety  Wincliell,  transverse  section  of  bundles. 

Fig.  48-75.  Camera  lucida  diagrams  of  hybrids  of  Wincliell  x  V.  rotundi¬ 
folia. 

Fig.  76.  Hybrid  (var.  Wincliell  x  V.  rotundifolia),  transverse  section  of 
bundles. 

Fig.  77.  Hybrid  (var.  Winchell  x  V.  rotundifolia),  transverse  section  of 
bundles. 

Fig.  78.  Hybrid  (var.  Winchell  x  V.  rotundifolia),  transverse  section  of 

internode. 


P  / zlssLp 


HYBRIDIZATION  OF  VITIS  ROTUNDIFOLIA 

INHERITANCE  OF  ANATOMICAL  STEM  CHARACTERS 


By  C.  F.  Williams,  Assistant 
Division  of  Horticulture 


In  plant  breeding^  especially  of  horticultural  crops,  little  or  no 
attention  lias  been  paid  to  anatomical  characters.  Only  those  of  weight, 
size,  color,  etc.,  and  such  physiological  characters  as  sugar,  starch,  and 
protein  content  have  been  studied.  In  fact,  rarely  is  a  cross  effected 
in  which  the  anatomy  of  the  parents  differs  sufficiently  to  make  possible 
any  comparison.  However,  in  hybridizing  Vitis  rotundifolia  with 
other  species  of  Vitas,  individuals  with  considerable  difference  in 
anatomy  have  been  successfully  crossed  and  the  hybrid  vines  obtained 
are  of  interest  from  this  viewpoint.  It  is  possible  to  examine  the  hybrid 
stems  not  only  for  such  superficial  characters  as  smoothness,  color, 
hardness,  size,  etc.,  but  also  for  the  fundamental  anatomical  structure 
which  is  the  basis  of  these,  and  therefore  the  critical  point  of  attack 
for  a  genetical  study. 

Vitis  rotundifolia ,  the  southern  muscadine  grape,  differs  considerably 
from  other  species  of  the  genus  Vitis,  especially  in  certain  of  the  stem 
characters.  Gray  (1)  has  divided  the  genus  Vitis  into  two  sub-genera. 
Under  one,  Muscadinia  (Planch.)  he  places  T  .  rotundifolia  and  under 
the  other,  Euvitis  (Planch.),  he  includes  all  other  grapes.  Small  (2) 
has  reserved  the  genus  Vitis  for  the  bunch  grapes  proper  and  makes 
a  separate  genus  for  the  muscadine  grape,  namely  Muscadinia  (Small). 
This  will  give  some  idea  of  the  extent  to  which  1  .  rotundifolia  species 
differ  from  the  other  species  of  Vitis.  Only  those  differences  that  affect 
the  material  under  discussion  will  be  considered  here. 

The  hybrid  vines  on  which  the  following  report  is  based  are  some 
grown  in  determining  the  limits  of  hybridization  of  1  itis  rotundif ol la 
with  other  species  of  Vitis.  The  particular  crosses  used  are  as  follows : 

TABLE  1.  PARENTAGE  OF  HYBRIDS 


Year 

Made 

No.  OF 
Vines 

Description  of  Cross 

1917 

1916 

26 

V.  vinifera  (var.  Malaga)  x  \.  rotundifolia 

7 

Y.  bourquiniana  (var.  Ilerbeinont)  x  ’S .  rotundifolia 

1912-16-18 

26 

Hybrid  (Labrusca  x  Aestivalis  x  Vinifera  var.  \\  in- 
chell)  x  V.  rotundifolia. 

1917 

1 

Hybrid  (Winchell  x  V.  rotundifolia)  x  V.  rotundifolia 

This  does  not  mean  that  these  are  the  only  crosses  of  V.  rotundifolia 
that  have  been  secured.  Other  hybrids  obtained  have  not  been  used 


4 


Hybridization  of  Yitis  Rotundifolia 


because  of  insufficient,  growth  in  some  cases,  and  death  of  the  vines  in 
others. 

These  vines  have  already  been  described  as  to  their  external  characters 
by  Detjen  (3).  This  paper  is  limited  to  the  gross  anatomy  of  the 
mature  one  year  canes  of  the  parent  vines  and  their  F 1  generation 
hybrids.  Material  was  collected  during  the  early  winter  of  1921-22,  and 
again  in  the  winter  of  1922-23.  In  order  to  have  a  uniform  basis  of 
comparison,  only  mature  one  year  canes  were  used.  Transverse,  radial, 
and  tangential  sections  were  cut  25-30  microns  thick,  from  the  middle  of 
the  internode  with  a  table  microtome.  Combination  stains  of  safranin 
with  Delafield’s  hematoxylin  or  with  light  green  were  used.  Table  2 
lists  the  different  species  and  varieties  of  Yitis  examined  during  this 
investigation. 


TABLE  2. 


SPECIES  OF 


VITIS  EXAMINED 


Species 

Variety 

No.  of  Vines 

Rotundifolia 

Pure  species  and  varieties 

12 

Vinifera 

Malaga 

O 

O 

Bourquinana 

Herbemont 

o 

Labrusca 

Concord 

2 

Labrusea 

Pure  species 

3 

Cinerea 

Pure  species 

1 

Arizonica 

Pure  species 

1 

Californica 

Pure  species 

1 

Aestivalis 

Pure  species 

5 

Aestivalis 

Norton 

1 

Munsoniana 

Pure  species 

1 

Champini 

Pure  species 

1 

Bicolor 

Pure  species 

1  ^ 

Simpsoni 

Pure  species 

1 

Don  ilia n a 

Pure  species 

1 

Hybrid 

(Labrusca  x  Aestivalis  x  Vinifera)  Winched 

O 

Hybrid 

(var.  Winchell  x  V.  rotundifolia) 

26 

Hybrid 

(V.  vinifera  x  V.  rotundifolia) 

26 

Hybrid 

(V.  bourquiniana  x  V.  rotundifolia) 

4 

Hybrid 

[Hybrid  (Wincliell  x  V.  rotundifolia)  x  V. 
rotundifolia.] 

1 

VITIS  ROTUNDIFOLIA 

Bark.  The  bark  of  V.  rotundifolia  is  greenish-grey  in  color,  rather 
smooth,  and  lias  numerous  lenticels.  It  is  very  persistent,  never 
shedding  on  the  young  wood,  and  on  the  very  old  wood  falling  off  in 
small  corky  flakes.  The  stems  of  the  young  vines  resemble  those  of 
maple  saplings  much  more  than  they  do  the  vines  of  the  Euvitis  group. 

Wood.  The  wood  is  very  hard  and  compact,  the  specific  gravity 
being  about  1.26  with  the  result  that  the  stems  will  sink  in  water.  The 
hardness  of  the  wood  is  especially  noticeable  in  pruning  as  the  stems 
are  much  more  difficult  to  cut  than  any  Euvitis  species. 

Pitli.  The  diameter  of  the  pith  column  is  very  small,  particularly 
as  compared  with  other  species  of  Yitis,  but  widens  out  at  the  node 


Hybridization  of  Yitis  Rotundifolia 


(Fig.  1),  at  which  there  is  no  diaphragm.  The  pith  is  light  green  in 
color  and  so  dense  that  Munson  (4)  in  describing  it  says,  “in  place 
of  pith  a  dense,  dark  green,  cellular,  nonfibrous  wood.”  The  cells  are 
uniform  in  size  in  the  node  and  internode,  very  thick  walled  and  pitted. 
Starch  is  stored  throughout  the  pith  column. 

Xylem.  In  T  .  rotundifolia  the  xylem  forms  a  greater  part  of  the 
stem  than  any  other  species  (Fig.  3).  Moreover,  it  is  distinguished 
from  Euvitis  species  by  the  character  of  the  wood,  which  is  composed 
o±  numerous  tracheae  or  vessels  embedded  in  a  mass  of  wood  fibers 
(Fig.  4),  both  of  which  are  smaller  in  diameter  than  those  of  other 
species,  except  V.  munsoniana.  These  fibers,  which  are  almost  round, 
are  septate  and  have  extremely  thick  walls  and  a  very  small  lumen. 
They  are  lignified  to  a  greater  degree  than  Euvitis  species  as  is  seen 
in  the  difficulty  in  cutting  the  stems,  in  the  staining  reaction,  and  in 
the  thick  walls. 

The  vessels  are  of  considerable  diameter  (Fig.  4),  although  the 
smallest  to  be  found  in  Yitis  species,  and  very  long,  due  to  many  of 
the  cross  walls  having  been  dissolved  away.  The  pitting  consists  of 
elongated  horizontal  slits  closed  by  thin  membranes,  as  is  common  among 
vines.  These  pits  are  of  two  sizes  depending  on  whether  the  vessel  is 
in  contact  with  wood  fibers  or  with  other  vessels.  Where  the  tracheae 
adjoin  wood  fibers,  the  pits  are  fairly  small  horizontal  slits  arranged  in 
vertical  rows.  If  one  vessel  is  in  contact  with  another,  the  slits  are 
very  long,  extending  almost  the  width  of  the  vessel.  Tyloses  occur  in 
the  vessels,  the  occluding  cells  being  thin  walled,  parenchymatous,  and 
not  pitted. 

Phlo'iem.  The  arrangement  of  the  elements  of  the  phloem  (hard  and 
soft  bast)  in  the  Muscadinia  species  differs  from  that  in  the  Euvitis 
species.  Figure  4  is  a  photomicrograph  of  a  cross-section  of  a  bundle 
showing  the  phloem  and  part  of  the  xylem  and  wood  rays.  Here  in 
V.  rotundifolia  the  phloem  as  seen  in  transverse  section  is  triangular 
in  outline  with  the  hard  bast  more  or  less  radially  disposed  on  the  sides 
of  the  soft  bast.  That  is,  the  portion  of  the  cambium  differentiating 
hard  bast  remains  about  the  same,  while  the  increased  circumference 
due  to  growth  is  adjusted  by  an  increase  in  the  amount  of  cambium  form¬ 
ing  soft  bast.  This  widening  of  the  phloem  accompanying  the  growth 
of  the  stem  results  in  a  triangular-shaped  mass  of  this  tissue.  I  lie 
hard  bast  is  composed  of  thick  walled  septate  wood  fibers.  The  cells 
of  the  soft  bast,  which  are  small  and  thin  walled,  are  somewhat  irregu¬ 
larly  disposed. 

External  to  the  phloem  there  is  a  small  round  bundle  of  scleienchvma 
fibers  forming  the  apex  of  the  triangle  mentioned  abo^  e.  These  fibeis 
are  extremely  long,  nearly  round,  very  thick  walled  with  small  lumen, 

and  septate. 


Hybridization  of  Vitis  Hotundifolia 


6 


Bays .  The  rays  of  all  Vitis  species  are  of  the  compound  wood  ray 
type  common  in  vines.  These  are  several  cells  wide  and  extend  longi¬ 
tudinally  through  the  internode  and  are  full  of  starch  (Fig.  4).  Those 
of  F.  rotundifolia  are  not  as  broad  as  the  ones  of  the  Euvitis  group. 
The  most  significant  characteristic  as  contrasting  with  the  other  Vitis 
species  is  that  portion  of  the  ray  extending  between  the  phloem  bundles. 
In  F.  rotundifolia  the  ray  in  this  region  expands  by  cell  multiplication 
to  fill  the  widening  gap  between  the  phloem  as  the  stem  increases  in 
circumference  (Fig.  4).  This  is  clearly  evident  in  the  arrangement  of 
the  cells  which  here  are  formed  in  tangential  rows,  contrasting  with 
the  radial  rows  of  the  ray  proper. 

Cortex.  The  cortex  in  F.  rotundifolia  is  in  sharp  contrast  with  that 
of  the  bunch  grape  type  (Fig.  4),  and  the  seat  of  this  difference  lies 
in  the  phellogen  or  cork  cambium.  In  the  Muscadinia  species  the 
phellogen  is  formed  immediately  under  the  epidermis,  and  produces 
internally  the  phelloderm  of  varying  thickness.  This  is  composed  of 
parenchymatous  cells  in  irregular  longitudinal  rows.  V.  rotundifolia 
is  further  characterized  by  the  presence  of  numerous  lenticels  which 
penetrate  the  cortex  for  a  considerable  depth  opposite  the  ends  of  the 
rays  (Fig.  4). 

VITIS  VINIFERA 

Bark.  The  hark  of  F.  vinifera  is  red-brown  to  greyish-brown  in 
color  on  the  young  wood.  It  is  finely  striated  and  sheds  in  long  fibrous 
plates. 

Wood.  The  wood  is  very  soft  and  porous.  It  is  light  in  weight 
(specific  gravity  less  than  1.0),  quite  brittle,  and  more  or  less  oblong 
in  cross  section. 

Pith.  The  diameter  of  the  pith  column  in  comparison  with  that  of 
the  stem  is  much  greater  than  in  the  case  of  F.  rotundifolia.  Figure 

5  of  F.  vinifera,  which  is  of  the  same  magnification  as  Figure  3  of 
F.  rotundifolia,  shows  the  proportion  of  the  tissues  in  section.  The 
pith  cells  of  V.  vinifera,  as  may  be  seen  in  a  comparison  of  these  two 
photomicrographs,  are  much  larger  and  thinner  walled.  The  pith  is 
dry  and  light  brown  in  color  and  contains  little  or  no  starch.  At  the 
node,  there  is  a  distinct  diaphragm  (Fig.  2)  composed  of  thick  walled 
lignified  cells  with  quitted  walls. 

Xylem.  The  elements  of  the  xylem  (vessels  and  wood  fibers)  are 
larger  in  diameter  than  are  those  of  F.  rotundifolia.  This  is  best  seen 
by  contrasting  Figure  5  with  Figure  3.  The  wood  fibers  are  more 
angular  in  section  and  not  as  thick  walled,  nor  as  lignified,  and  are 
in  more  distinct  radial  rows  (Fig.  6).  There  are  more  vessels  and 
they  are  larger  in  this  species  than  in  F.  rotundifolia,  but  the  sculptur¬ 
ing  is  similar.  Tyloses  in  the  vessels  are  common  in  this  species.  One 
occluded  vessel  may  be  seen  in  cross  section  at  the  lower  right  in  Figure 

6  and  several  in  Figure  5. 


Hybridization  of  Yitis  Rotundifolia  7 

Phloem.  '  Hie  arrangement  of  the  phloem  in  V.  vinifera  is  typical 
tor  all  Euvitis  species.  Figure  6  is  of  the  phloem  portion  of  a  bundle 
of  1  .  vinifera  and  should  be  contrasted  with  Figure  4  of  V.  rotundifolia 
which  is  of  the  same  magnification.  In  transverse  section  it  is  almost 
square  in  outline  and  is  composed  of  alternating  tangential  layers  of 
hard  and  soft  bast.  Thus  in  contrast  with  the  Muscadinia  type,  the 
cambium  forms  first  a  layer  ot  soft  hast  and  then  a  layer  of  hard 
bast,  each  several  cells  deep,  and  repeating  this  differentiation  until 
there  may  he  as  many  as  six  or  seven  pairs  of  layers.  The  cells  are 
arranged  in  radial  rows  and  are  of  larger  size  than  those  of  V.  rotundi¬ 
folia.  The  hard  bast  cells  are  more  angular  in  outline  and  thinner 
walled  than  in  that  species,  and  the  soft  hast  cells  are  much  larger. 
External  to  the  phloem  of  the  bundle  is  a  semicircular  column  of 
sclerencliyma  fibers.  They  contrast  with  those  of  V.  rotundifolia  in 
being  arranged  in  larger  bundles  which  are  semicircular,  in  being 
larger  in  diameter  and  very  angular,  and  thinner  walled. 

Bays.  The  rays  of  1  .  vinifera  (Fig.  6)  are  compound  wood  rays 
as  in  other  Yitis  species,  though  considerably  wider  than  those  of  V. 
rotundifolia.  In  contrast  with  these  latter,  they  extend  between  the 
phloem  bundles  without  widening  through  cell  multiplication.  Thus, 
the  growth  of  the  stem  causes  the  cells  to  become  pulled  tangentially 
and  distorted,  especially  at  the  ends  of  the  rays. 

Cortex.  As  the  cortex  of  Euvitis  species  is  shed,  the  appearance  in 
the  cross  section  of  the  mature  one  year  wood  is  quite  different  from 
that  of  the  Muscadinia  species  (Fig.  6).  The  phellogen  forms  im¬ 
mediately  external  to  the  phloem  and  inside  of  the  sclerencliyma  bundles. 
This  layer  of  cork  cells  cuts  off  the  water  supply  of  the  tissues  outside 
of  it,  causing  them  to  dry  out  and  fall  off.  As  the  stem  increases  in 
circumference,  there  is  no  multiplication  of  cells  as  in  V.  rotundifolia 
so  that  the  cells  are  much  distorted  and  torn.  Thus  the  cells  in  this 
region  are  very  irregular  and  compacted.  There  are  no  lenticels  present 
in  this  type  of  stem,  the  open  ends  of  the  rays  serving  this  purpose  and 
often  at  the  time  that  the  bark  is  shed,  simulating  them  in  appearance. 

V.  VINIFERA  X  V.  ROTUNDIFOLIA  HYBRIDS 

Baric.  Most  of  the  hybrids  of  this  cross  have  a  light  greyish-brown 
bark  which  is  obscurely  striated  and  has  few  lenticels,  and  sheds  in 
small  flakes  rather  than  in  fibrous  plates  as  in  I .  vinifera.  1  lie  appear¬ 
ance  of  the  stems  is  rather  smoother  than  that  ot  either  parent  due  to 
the  smaller  number  of  lenticels  and  a  more  obscure  striation.  the 
number  of  lenticels  varies  inversely  with  the  extent  to  which  the  bark 
is  shed,  some  vines  having  a  more  or  less  persistent  bark  with  many 
lenticels,  and  others  having  a  loose  bark  and  fewer  lenticels  and  moic 

striations. 

Wood.  The  wood  is  intermediate  between  the  two  parents  and  is 


8 


Hybridization  of  Vitis  Rotundifolia 


usually  somewhat  brittle.  It  is  not  as  hard  as  V.  rotundifolia  but 
seldom  as  soft  as  V.  vinifera.  The  specific  gravity  in  all  but  two 
cases  was  greater  than  1.0,  and  hence  fresh-cut  wood  sinks  in  water. 
In  cross  section  the  stem  is  more  or  less  elliptical  rather  than  oblong 
as  the  V.  vinifera .  parent,  hut  not  often  as  round  as  in  V.  rotundifolia. 

Pith.  The  diameter  of  the  pith  column  of  the  hybrids  is  a  little  less 
than  the  average  of  the  two  parents  and  it  varies  in  color  from  light 
green  to  light  brown.  The  size  of  the  pith  cells  at  the  internode  is 
about  the  same  as  in  V.  rotundifolia ,  hut  those  at  the  node  vary  in 
size  with  the  extent  to  which  there  is  an  expression  of  a  diaphragm. 
In  a  small  percentage  of  the  hybrids  (two  of  the  twenty-six  examined) 
there  was  a  distinct  diaphragm  at  the  node  visible  to  the  naked  eye. 
In  the  others  there  was  a  tendency  for  the  cells  at  the  node  to  he  com¬ 
pacted  in  a  vertical  direction.  In  order  to  arrive  at  some  conclusion  as 
to  the  extent  of  this  compaction  the  number  of  cells  in  a  given  area  in 
an  average  region  of  the  longitudinal  section  was  counted.  The  results 
are  given  below : 

TABLE  3 


Vine 

Number  of  Cells  at 

Ratio 

Node 

Internode 

Vinifera 

227 

S9 

2.54:  1 

Rotundifolia 

135 

136 

1.00;  1 

Hybrid  with  diaphragm 

138 

40 

3.45:  1 

Hybrid  without  diaphragm 

139 

88 

1.58:  1 

The  above  table  would  indicate  that  the  cells  of  the  internode  resemble 
the  V .  rotundifolia  parent,  and  that  the  cells  at  the  node  are  more  or 
less  influenced  by  the  V.  vinifera  parent.  It  was  also  observed  that 
the  increase  in  the  number  of  cells  at  the  node  was  due  to  a  lessening 
of  their  vertical  height  with  little  change  in  their  horizontal  diameter. 

Xylem.  The  character  of  the  xylem  is  intermediate  between  that 
of  the  parents.  The  hybrids  vary,  however,  through  all  the  range,  one 
in  fact  going  beyond  Ik  vinifera  in  size  of  cells  and  number  of  vessels. 
The  fibers  are  larger  than  in  V.  rotundifolia  but  not  as  angular  as  in 
V.  vinifera.  The  trachese  also  are  larger  than  those  of  V.  rotundifolia 
and  the  sculpturing  is  that  typical  of  Vitis  species.  Some  of  the 
variation  in  the  size  and  number  of  vessels  of  the  hybrids  is  shown  in 
Figures  7-10,  and  13-38. 

Phloem.  In  hybrids  the  arrangement  of  the  elements  of  the  phloem 
as  seen  in  the  transverse  section  covers  the  ranges  of  both  parents. 
There  is,  however,  a  greater  resemblance  to  the  staminate  parent  in  the 
majority  of  cases.  In  most  of  the  vines  there  is  a  radial  row  of  hard 
bast  of  greater  or  less  extent  on  the  sides  of  the  phloem  bundle  (Figs. 
7  and  8).  In  addition  to  this,  there  is  also  a  tendency  for  tangential 


Hybridization  of  Vitis  Kotundifolia 


9 


layers  of  hard  bast  to  appear  in  the  bundle  itself,  either  starting  from 
one  side  or  both  sides  and  not  reaching  all  the  way  across,  or  extending 
all  the  way  across  the  bundle  (Fig.  9).  In  only  two  instances  did 
the  bundle  resemble  that  of  Euvitis  species,  one  of  which  is  shown  in 
Figure  10.  It  is  lemarkable  that  the  pattern  of  the  phloem  bundle  as 
seen  in  cross  section  varies  in  the  same  stem  to  a  very  considerable 
extent,  showing  a  lack  of  fixation  of  this  character  in  a  given  stem 
(see  Figs.  13-38).  Some  of  the  vines,  however,  are  quite  uniform  in 
their  pattern.  Inasmuch  as  the  cambium  determines  the  formation  of 
hard  or  soft  bast  under  unknown  influences,  in  cases  where  the  pattern 
in  which  these  elements  are  laid  down  varies  in  the  same  stem,  it  would 
seem  that  the  cambium  of  the  stem  must  vary  in  its  constitution. 


The  size  of  the  cells  of  the  hard  and  soft  bast  is  intermediate,  as  is 
the  thickness  of  their  walls,  and  their  shape.  The  sclerenchyma  bundle 
is  more  V.  rotundifolia  in  character,  though  usually  of  larger  size  than 
this  parent. 

Figui  ’es  11  to  38,  inclusive,  are  camera  lucida  diagrams  of  the  same 
magnification  of  V.  vinifera ,  V.  rotundifolia ,  and  their  hybrids.  The 
hard  bast  of  the  phloem  (also  the  bundle  of  sclerenchyma  fibers)  is 
shown  stippled.  Figures  13  to  38  show  different  degrees  of  inter¬ 
mediacy  of  character  in  the  hybrids.  Figures  13  and  15  show  two 
adjacent  bundles  each  with  contrasting  arrangements  of  the  hard 
and  soft  bast.  Such  cases  are  quite  common  among  the  hybrids. 
Figures  14,  20,  25,  and  33  show  a  progression  in  the  range  between 
the  two  types  of  arrangement.  Only  in  Fgures  33  and  35  has  the  F. 
vinifera  character  approached  dominance.  Figure  34  shows  the  elements 
of  the  hard  bast  scattered  indiscriminately  through  the  soft  bast. 

Rays.  The  character  of  the  intervascular  ray  varies  with  the  char¬ 
acter  of  the  phloem.  If  the  bundle  is  triangular  as  in  TT.  rotundifolia 
the  ray  immediately  widens  out  by  cell  multiplication  as  in  this  parent 
(Fig.  7),  but  if  the  phloem  bundle  is  broad  and  square  the  ray  extends 
out  without  increasing  in  width  as  in  V.  vinifera.  (Fig.  10).  In  some 
cases  the  ray  extends  part  of  the  depth  of  the  bundle  before  widening 
out,  showing  most  exactly  the  intermediate  character  (Figs.  8  and  9). 

Cortex.  The  cortex  in  the  hybrids  shows  less  fixation  of  a  definite 
character  than  any  other  part  of  the  stem,  varying  from  a  close 
resemblance  to  the  staminate  parent  to  a  similarity  to  the  pistillate 
parent.  In  most  cases,  the  cortex  is  very  much  like  that  of  the  1  . 
rotundifolia  species.  Only  the  two  that  have  the  "V .  vinifera-like 
phloem  have  a  cortex  resembling  that  parent,  In  many  ot  the  ones 
there  is  a  great  variation  in  the  same  stem,  one  side  being  quite  different 
from  the  other,  or  having  patches  of  V.  vinifera-like  cortex  with  large, 
loose,  torn  cells  outside  of  a  cortex  otherwise  resembling  V.  rotundifolia 
(Fig.  8  and  9).  In  the  examples  illustrated  in  Figures  7  and  8  the 
type  of  cortex  shown  is  not  typical  for  the  entire  section  of  the  stem 


10 


Hybridization  of  Vitis  Kotundifolia 


but  only  for  a  small  number  of  bundles,  more  striking  because  of  their 
irregular  occurrence. 

The  indeterminate  location  of  the  pliellogen  seems  to  be  the  cause  of 
this  variation.  It  appears  in  the  photomicrographs  as  a  whitish  layer 
due  to  the  stain  washing  out  of  the  suberized  tissues.  Its  position 
varies  not  only  in  different  vines  but  usually  in  the  same  vine  (Fig.  7). 
In  some  cases,  it  is  just  under  the  epidermis  as  in  V.  rotundifolia.  In 
other  cases,  it  is  inside  of  the  sclerenchyma  bundle  as  in  the  other 
parent  (Fig.  10).  Quite  often  there  is  an  isolated  layer  of  suberized 
tissue  surrounding  only  one  bundle  of  sclerenchyma  fibers  (Fig.  29). 
Frequently  all  three  of  these  positions  for  the  pliellogen  are  found  in 
the  same  stem,  and  in  some  instances  at  the  same  point  in  the  stem. 
Usually  the  cortex  inside  the  cork  cambium  resembles  the  V.  rotundi¬ 
folia  parent,  and  that  outside  the  F.  vinifera  parent  (Fig.  9).  Lenticels 
were  present  only  where  the  pliellogen  is  immediately  under  the 
epidermis.  This  scattered  distribution  of  the  cork  cambium  is  respon¬ 
sible  for  the  exfoliation  of  the  bark  in  small  flakes. 

In  Figures  11  to  38  the  pliellogen  is  shown  in  solid  black.  Figures 
11  and  12  represent  the  parents,  and  Figures  13  to  38  the  hybrids, 
which  show  all  degrees  of  the  cork  cambium  character  expressed  in 
the  parents.  Bundles  diagrammed  are  more  or  less  typical  for  the 
particular  stem,  but  do  not  by  any  means  represent  the  condition  of 
each  bundle  of  the  stem.  In  Figure  13,  for  example,  the  pliellogen 
occurred  outside  of  only  a  few  bundles  at  this  particular  location 
which  is  used  to  illustrate  the  arrangement  of  hard  and  soft  bast  in 
the  phloem.  Such  cases  as  shown  in  Figures  19,  24,  37,  and  similar 
ones,  usually  occurred  only  in  small  patches  of  the  circumference  of 
the  transverse  section.  In  Figure  31  isolated  suberized  cells  are 
scattered  through  the  cortex. 

VITIS  BOURQUINIANA,  Variety  Herbemont 

The  stem  of  F.  loourquiniana  so  closely  resembles  that  of  F.  vinifera 
that  a  detailed  description  of  it  is  unnecessary  in  this  place.  If  any 
difference  exists  in  the  characters  in  question  it  is  perhaps  that  the 
cells  have  thinner  walls  (Fig.  45). 

V.  BOURQUINIANA  X  V.  ROTUNDIFOLIA  HYBRIDS 

It  was  possible  to  examine  only  four  of  the  hybrids  of  this  cross. 
The  expression  of  the  intermediate  character  is  similar  to  that  in  the 
F.  vinifera  hybrids.  There  is,  however,  no  example  of  the  phloem 
bundle  resembling  that  of  the  Euvitis  parent  and  the  resemblance  was 
predominantly  toward  the  other  parent.  In  view  of  the  small  number 
of  vines  studied,  this  was  hardly  significant. 

Diagrams  of  these  hybrids  are  shown  in  Figures  39  to  44,  inclusive, 
Figures  39  and  40  being  from  one  vine,  and  Figures  43  and  44  from 


Hybridization  of  Yitis  Rotimsdifolia 


11 


another  single  vine.  In  these  cases  the  bundles  were  not  adjacent  but 
came  from  different  parts  of  the  same  transverse  section.  The  pair  in 
Figures  39  and  40  show  well,  not  only  the  tendency  to  form  alternate 
layers  of  hard  and  soft  bast,  but  also  (Fig.  40)  the  squaring  up  of  the 
bundle  due  to  the  intervascular  ray  not  widening  out  by  cell  multipli¬ 
cation.  Figure  43  shows  the  varying  amount  of  phellogen  in  the  same 
stem.  Figure  42  is  of  interest  because  of  the  small  amount  of  hard 
bast  fibers  present. 

V  A I  i  I E  T  Y  WINCIIELL 


(Hybrid  of  Y.  labrusca,  Y.  aestivalis,  Y.  vinifera) 


While  it  has  not  been  possible,  as  yet,,  to  pick  out  distinctive  specific 
characters  of  the  stem  on  the  basis  on  which  this  study  is  made  for  the 
different  species  of  Yitis,  the  anatomical  characters  of  Winchell  resem¬ 
ble  most  closely  of  the  three  parents,  those  of  F.  aestivalis,  and  the  dif¬ 
ferences  noted  in  the  following  description  vary  from  the  V.  vinifera 
species  in  that  direction. 

Baric.  The  bark  is  reddish-brown  in  color,  striated  and  shedding  in 
long  fibrous  plates. 

Wood.  The  wood  is  soft  and  brittle  and  quite  porous.  It  is  light 
in  weight  and  almost  round  in  cross-section. 

Pith.  The  pith  column  is  very  large  in  diameter  and  larger  in  pro¬ 
portion  to  the  diameter  of  the  stem  than  F.  vinifera  (Fig.  46).  In  this, 
it  resembles  the  F.  labrusca  parent.  The  pith  is  dry  and  loose,  light- 
brown  in  color,  and  composed  of  large,  thin-walled  cells.  There  is  a 
thick  diaphragm  at  the  node  composed  of  compact  lignified  pith  cells 
with  thick  walls  having  simple  pits. 

Xylem.  The  xylem  of  this  variety  is  quite  like  that  of  F.  vinifera, 
but  the  bundle  is  not  as  deep  in  proportion  to  the  stem  diameter  on 
account  of  the  large  pith.  The  cells  are  a  little  smaller  and  not  as 
thick  walled.  (Fig.  46.) 

Phloem.  The  phloem  is  in  the  typical  arrangement  for  Euvitis 
species.  The  cells  are  more  uniform  in  size  and  smaller  than  T  .  vini¬ 
fera.  The  fibers  of  the  sclerenchyma  bundle  differ  very  little  from 
those  of  F.  vinifera  (Fig.  47). 

Cortex.  The  cortex  in  this  species  differs  but  little  from  that  of  1  . 


vinifera  as  above  described. 

V.  VAR.  WINCHELL  X  V. 


IK )  T  U  N  D I F  Q  LI  A  HYBRII  >S 


Bark.  Most  of  the  hybrids  of  this  cross  have  a  rather  smooth,  red¬ 
dish-brown  bark,  darker  in  color  than  the  1  .  vinifera  hybrids.  On 
these  the  bark  sheds  either  in  long  fibrous  plates  or  in  smaller  flakes. 
Others  of  the  cross  have  a  persistent  bark  which  is  lighter  in  color 
and  more  of  a  greyish-brown,  with  many  lenticels. 


12 


Hybridization  of  Yitis  Rotundifolia 


Wood.  The  wood  is  soft  and  very  brittle,  snapping  off  easily  at  the 
node  and  only  a  little  less  easily  at  the  internode.  The  section  of  the 
stem  is  almost  round  in  outline. 

Pith.  The  diameter  of  the  pith  varies  widely  between  that  of  the 
two  parents,  which  are  extremes  in  either  direction  for  size  of  all  the 
vines  examined.  In  color,  some  have  a  light  brown  pith  and  others 
light  green  as  in  V.  rotundifolia.  In  this  latter  case,  the  pith  is  usually 
continuous  without  a  distinct  diaphragm  at  the  node.  The  others  have 
a  more  or  less  complete  diaphragm.  Of  the  twenty-six  examined,  eleven 
have  definite  diaphragms  at  the  node  visible  without  the  use  of  the  lens. 
In  those  with  continuous  pith  the  cells  at  the  node  were  compacted  and 
lignified  to  a  varying  extent. 

Xylem.  The  xylem  is  more  nearly  like  that  of  the  variety  Winchell, 
especially  in  the  size  and  shape  of  cells,  although  the  walls  are  thicker 
than  those  of  this  variety. 

Phloem.  In  these  hybrids  there  is  a  great  variation  in  the  pattern 
of  the  phloem  as  examined  in  the  transverse  section.  In  eleven  of  the 
twenty-six  the  hard  and  soft  hast  are  disposed  in  a  manner  similar  to 
that  in  the  Euvitis  species.  In  the  others,  there  is  more  or  less  simi¬ 
larity  to  the  staminate  parent,  although  there  is  a  greater  tendency  for 
the  hard  bast  to  form  tangential  layers  across  the  bundle  regardless  of 
the  shape  of  the  bundle  than  in  the  case  of  V.  vinifera  hybrids.  The 
bundle  of  sclerenchyma  fibers  varies  with  the  type  of  phloem  bundle. 
The  square  Wincliell-like  bundle  is  accompanied  by  a 'bundle  of  scle¬ 
renchyma  fibers  similar  to  the  same  species. 

The  camera  lucida  diagrams  shown  in  Figures  48-75  inclusive,  repre¬ 
sent  bundles  from  each  of  the  hybrids  of  this  cross;  Figures  55  and  56 
being  from  the  same  vine,  and  Figures  60  and  61  from  another  single 
vine.  The  range  of  the  intermediate  character  of  the  hard  hast  is  shown 
by  Figures  49,  51,  53,  56,  60  and  66.  This  is  also  well  shown  in  the  one 
vine  represented  by  Figures  55  and  56,  or  in  Figure  62.  The  vines 
represented  by  Figures  55  and  58  are  interesting  because  of  the  scarcity 
of  hard  bast  present  in  the  phloem. 

Pays.  The  rays  show  the  same  correlation  with  the  shape  of  the 
phloem  tissue  as  in  the  case  of  the  V.  vinifera  hybrids,  that  is,  the 
intervascular  ray  expands  by  cell  multiplication  when  the  phloem 
bundle  is  sufficiently  triangular  in  shape  to  cause  a  tangential  strain 
(Fig.  76). 

Cortex.  The  cortex  of  these  hybrids  is  extremely  irregular.  The 
predominant  character  is  the  excessive  amount  of  cork  cambium  at 
scattered  points  in  the  transverse  section  (Fig.  77).  This  lack  of  defi¬ 
nite  character  for  the  phellogen  is  greater  than  in  the  case  of  the  V. 
vinifera  hybrids.  In  some  instances,  the  entire  thickness  of  the  cortex 
seems  to  he  completely  of  suberized  tissue  (Figs.  76  and  78). 

The  diagrams  in  Figures  48-75  illustrate  the  various  amounts  and  ar- 


13 


Hybridization  of  Yitis  Rot  undifolia 

rangements  of  the  cork  cambium.  The  quantity  varies  from  that  shown 
in  Figure  51  to  that  of  Figure  58,  and  its  position  in  relation  to  other 
tissues  varies  greatly  in  depth  as  shown  in  Figures  52  and  63.  In 
Figures  68-74  inclusive,  the  drying  out  of  the  cells  outside  of  the  suber- 
ized  layer  was  so  complete  that  this  portion  of  the  cortex  fell  off  either 
before  or  after  cutting  the  section.  In  each  of  these  cases,  the  phellogen 
was  located  inside  of  the  sclerenchyma  bundles. 


HYBRIDS  VAR.  WINCHEL1 _ V.  ROTUNDI FOLIA  HYBRID  X  Y. 

ROTUNDIFOLIA 

There  is  only  one  vine  of  this  cross  and  it  is  so  small  and  weak 
that  it  would  be  unwise  to  draw  any  conclusions  from  it.  It  is,  how¬ 
ever,  predominantly  V.  rotundifolia  in  character,  which,  inasmuch  as 
this  is  the  staminate  parent,  would  indicate  its  hybrid  character.  The 
stem  and  bark  resemble  this  parent  and  the  pith  is  small,  light  green 
and  continuous.  The  transverse  section  of  the  stem  shows  strongly  the 
V.  rotundifolia  parentage  in  the  pattern  of  the  phloem  bundle,  the 
proportion  of  elements  and  the  presence  of  lenticels.  At  one  point  of 
this  section  there  is  an  excessive  amount  of  dry  cortex  outside  of  the 
phelloderm  resembling  the  hybrids  of  the  Fi  generation. 


DISCUSSION 

It  has  been  possible  in  the  hybridization  of  Yitis  species  to  cross 
individuals  that  have  considerable  difference  in  the  anatomy  of  the 
stem  structure.  These  characters  are  inherited  by  the  hybrid  offspring 
so  that  there  is  an  opportunity  to  study  the  inheritance  of  characters 
that  are  of  greater  fundamental  importance  from  a  genetical  viewpoint 
than  such  superficial  ones  as  color,  weight,  size,  etc.  FTo  doubt,  some 
of  these  characters  may  be  correlated  with  other  external  morpho¬ 
logical  ones,  but  the  study  of  the  inheritance  of  these  essential  struc¬ 
tural  characters  should  be  of  great  value  to  an  understanding  of  the 
principles  of  heredity. 

The  varying  degree  of  expression  of  the  blended  intermediate  char¬ 
acter  in  the  offspring  would  probably  be  best  explained  by  a  multiple 
factor  hypothesis.  The  small  number  of  individuals  available  and  the 
fact  that  only  the  F^  generation  has  been  studied  would  make  it  im¬ 
possible  to  draw  any  definite  conclusions. 

It  is  very  significant,  however,  that  the  intermediate  condition  ot 
the  anatomical  stem  characters  varies  in  degree  not  only  in  the  differ¬ 
ent  hybrid  vines,  but  also  in  the  same  individual.  It  is  a  striking  fact 
that  neighboring  and  even  adjacent  bundles  in  the  same  transverse  sec¬ 
tion  may  resemble  different  parents.  In  such  small  stems,  this  con¬ 
dition  cannot  be  explained  as  a  response  to  external  environmental 
factors.  This  condition  approaches  a  chimera  but  differs  from  it  in 
the  lack  of  total  dominance  of  expression  of  either  parent.  Actually 
there  are  different  degrees  of  blending  in  the  same  individual. 


14 


Hybridization  of  Yitis  Rotundifolia 


are  here  several  interdependent  characters.  Changes  affecting  one  of 
them  therefore  will  to  some  extent  influence  the  others.  Where  the 
degree  of  inheritance  of  the  intermediate  condition  is  uniform  for 
each  character  of  the  individual,  there  is  a  stem  that  is  fairly  uniform 
in  its  composition.  On  the  other  hand,  where  the  degree  of  inheritance 
of  the  different  characters  varies  for  the  individual,  the  influence  of 
the  related  characters  results  in  a  complex  condition.  It  is  necessary 
to  consider  this  on  the  basis  of  the  generative  tissue  of  the  cambium. 
It  would  appear  that  the  cambium  varies  in  its  hereditary  composition, 
a  difficult,  thing  to  explain  or  believe. 

It  would  probably  be  advisable  if  possible  to  determine  the  immedi¬ 
ate  causes  influencing  the  formation  of_  hard  bast  in  the  phloem,  and 
the  formation  of  phellogen.  Knowing  these  influences,  it  might  be 
possible  to  find  a  hereditary  factor  or  factors  which  would  control  these 
characters. 

In  regard  to  the  formation  of  phellogen,  Douliot  (5)  finds  that  the 
cork  in  the  stem  may  be  superficial,  pericylic  or  intermediate  in  origin. 
In  the  parents  of  the  crosses  described  here,  the  Euvitis  species  have 
the  cork  cambium  pericylic,  and  the  Muscadinia  species  superficial. 
However,  the  lack  of  an  intermediate  condition  for  this  character  in 
the  hybrids  of  the  Fi  generation  but  rather  a  proliferation  of  suber- 
ized  tissue  would  indicate  the  inheritance  of  a  tendency  to  form  cork 
cambium  in  both  locations. 

Priestley  (6)  has  studied  the  formation  of  phellogen  from  the  casual 
standpoint,  finding  that  it  is  related  to  “ 1 ,  the  blocking  of  a  parenchy¬ 
matous  surface  usually  by  a  deposit  of  suberin  or  cutin  formed  in  the 
presence  of  air;  2,  the  accumulation  of  sap  at  the  parenchymatous 
surface  thus  blocked;  3,  the  consequent  development  and  activity  of  a 
phellogen  amidst  this  parenchyma.”  This  would  hold  true  in  the  case 
of  the  parents  of  these  hybrids.  In  Muscadinia  species  the  sap  can 
move  outward  in  the  stem  to  the  epidermis  where  it  is  blocked  and  phel¬ 
logen  subsequently  formed.  In  the  Euvitis  stem  the  cortical  cells  are 
destroyed  during  the  expansion  of  the  stem  and  air  enters  as  deep  as 
the  endodermis  and  the  cork  cambium  is  formed  here.  In  the  hybrids 
where  a  combination  of  these  conditions  exist,  it  is  difficult  to  explain 
phellogen  formation  as  due  to  these  causes,  especially  in  those  cases 
where  there  is  a  layer  of  isolated  phellogen  around  a  bundle  of  scleren- 
chyma  fibers,  or  where  there  are  two  layers  of  phellogen.  In  other 
cases  it  would  appear  that  the  location  of  the  cork  cambium  depended 
on  the  ability  of  the  cortical  cells  to  multiply  and  thus  present  a  layer 
of  parenchymous  cells  impervious  to  the  air.  Such  an  explanation 
practically  removes  the  phellogen  from  direct  inheritance  by  hereditary 
factors,  the  hereditary  factors  controlling  only  the  cambium  and  the 
tissues  formed  by  it,  and  the  phellogen  formation  being  controlled  by 
air  and  moisture. 

The  significance  of  the  different  degree  of  intermediate  inheritance 


Hybridization  of  Yitis  Rotundifolia 


15 


in  the  hybrids  of  V.  rotundifolia  with  V.  vinifera  var.  Malaga,  and  with 
\  itis  hybrid  var.  Winchell  has  not  been  determined.  The  difference 
between  T  .  rotundifolia  and  each  of  these  is  apparently  about  the  same 
as  far  as  actual  characters  are  concerned.  Whether  the  genetical  dif¬ 
ference  is  greater  in  case  of  var.  Winchell  crosses  due  possibly  to  its 
own  hybrid  nature,  is  still  to  be  investigated.  Unfortunately,  indi¬ 
viduals  of  crosses  between  T  .  rotundifolia  and  each  of  the  species  rep¬ 
resented  in  the  pedigree  ot  Winchell  cannot  at  this  time  be  examined. 
A  study  of  V.  labrusca  and  V.  aestivalis  has  given  no  additional  in¬ 
formation. 

This  study  of  the  anatomy  of  the  stems  of  Yitis  species  probably 
explains  the  difficulty  of  rooting  Muscadine  cuttings,  and  grafting  V. 
vinifera  on  Muscadinia  species  roots.  It  may  be  possible  to  develop  a 
hybrid  root  resistant  to  phylloxera  and  on  which  the  V.  vinifera  may 
be  easily  grafted. 

SUMMARY 


Idle  stems  of  the  subgenera  of  Yitis,  namely,  Muscadinia  and  Euvitis, 
have  distinctly  different  anatomical  characters. 

These  characters  may  be  summarized  as  follows : 


Cli  a  meter 

Muscadinia 

Euvitis 

Bark 

persistent 

shedding 

Lenticels 

present 

absent 

Pith  _ 

small,  of  thick-walled  cells — 

large,  of  thin-walled  cells 

I  fiaphragm 

absent  at  node 

present  at  node 
larger,  thin-walled 

Wood  fillers 

small  diameter,  thick-walled- 

Phloem  section _ 

triangular 

square 

Hard  hast 

outlines  soft  radially 

in  alternate  layers  with 
soft  fibers 

Sclerenchyma 

small  bundle  of  round  thick- 

large  bundle  of  angular 

fibers 

walled  fibers 

fibers 

Rays  in  inter- 
vascular  region. 

widen  by  cell  increase 

continue  the  same  width 

Phelloderm 

present _ 

absent 

Pliellogen 

immediately  under  epidermis. 

just  outside  of  phloem 

Sp.  gravity  of 

greater  than  water 

less  than  water 

fresh  cut  wood- 

In  crosses  between  the  species  of  these  subgenera,  the  lnbiids  inluiit 
the  anatomical  characters  as  well  as  the  morphological  cliai  actus,  aiu 
just  as  strikingly  as  the  external  characters  usually  studied. 

These  characters  in  the  hybrids  were  intermediate  resembling  either 
parent  with  varying  degree,  but  with  possibly  greater  resemblance'  to 
the  V.  rotundifolia  parent. 

In  the  hybrids  with  var.  Winchell  there  was  less  resemblance  to  the 
U.  rotundifolia  parent  than  in  the  1  .  vinifera  hybiids. 

The  degree  of  the  expression  of  the  intermediate  condition  was  about 
uniform  in  all  the  characters  of  any  one  vine.  That  is,  a  vine  with 


16 


Hybridization  of  Vitis  Rotundifolia 


more  resemblance  to  one  parent  in  any  character  had  more  resemblance 
to  that  parent  in  the  other  characters. 


1. 


O 


o 

O. 


Gray,  Asa  : 

1008.  Gray’s  New  Manual  of  Botany.  Ttli  edition.  New  York.  926  p. 
Small  : 

1913.  Flora  of  the  Southeastern  United  States.  2d  edition.  New  York. 
1394  p. 


Det.ien.  L.  R. : 

1919.  Some  Ft  Hybrids  of  Vitis  Rotundifolia  with  Related  Species  and 
Genera.  N.  C.  Agricultural  Experiment  Station  Technical  Bulletin 
18,  Figs.  33,  p.  50. 


4.  Munson,  T.  V. : 

1909.  Foundations  of  American  Grape  Culture,  Denison  Tex.  251  p. 

5.  Douliot.  H. : 

1889.  Recherches  sur  le  Periderme.  In  Ann.  des  Sci.  Nat.  Vile  Ser.  10. 
pp.  325-395. 

6.  Priestley,  J.  H.,  and  Woffender,  Lettice.  M. : 

1922.  Physiological  Studies  in  Plant  Anatomy,  V.  Causal  Factors  in 
Cork  Formation.  In  New  Phytologist  XXI  No.  5.  pp.  252-268,  Bibli¬ 
ography.  p.  267-268. 


17 


Hybridization  of  Vitis  Rotundifolia 


Fig.  1.  Yuris  Rotundifolia,  Longitudinal  Section  Through  the  Node 


18 


II YBKIDIZATICN  CF  VlTIS  ROTUNDIFOLIA 


Fig.  3.  Vitis  Rotundifolia,  Transverse  Section  of  Internode 


Hybridization  of  Vitis  Rotundifolia 


19 


Byn|  • 


BpqHgtflJta 


H 


h 


■g 


Fig.  4.  Vitis  Rotgndifoi^ .Transverse  Section  oi ;  Biindls  (p)  Phkllogen.  (/> 

SCLERENCHYMA  FIBERS,  (7l)  HARD  BAST,  (S)  bOFT  DASI, 

VESSBLTi. 


20 


Hybridization  of  Vitis  Rotundifolia 


Fig.  5.  Vitis  Vinifera,  Transverse  Section  of  Internode. 


Hybridization  of  A  itis  Rotundifolia 


21 


Fig.  6.  Vitis  Vinifera,  Transverse  Section  of  Bundle,  (p)  Phellogen.  i/i 

SCLERENCHYMA  FIBERS,  ( ll )  HARD  BAST,  (S)  SOFT  BAST,  (C)  CAMBIUM,  O')  HAY  , 

( v )  Vessel. 


22 


Hybridization  of  Vitis  Hotundifolia 


Fig.  7.  Hybrid  (V.  vinifera  x  V.  rotundifolia)  ,  Transverse  Section  of  Bundles. 


Hybridization  of  Vitis  Rotundifolia 


23 


Fig.  8.  Hybrid  (V.  vinifera  x  V. 


rotundifolia)  ,  Transverse  Section  of  Bundles. 


24 


Hybridization 


Vitis  Rotundifolia 


of 


Fig.  9.  Hybrid  (V.  vinifera  x  V.  rotundifolia)  ,  Transverse  Section  of  Bundles. 


Hybridization  of  Yitis  Rotundifolia 


25 


Fig.  10.  Hybrid  (V.  vinifera  x  V.  rotundifolia)  ,  Transverse  Section  of  Bi  ndles. 


26 


Hybridization  of  Vitis  Rotundifolia 


Fig.  45.  V.  Botjrquiniana,  Transverse  Section  of  Bundles 


BRIDIZATION  OF  \  ITIS  RoTUNDIFOLIA 


Fig.  46.  Variety  Winchell,  Transverse  Section  of  Internodi 


28 


Hybridization  of  Vitis  Rotundifolia 


Fig.  47. 


Variety  Winchell,  Transverse  Section  of  Bundles 


bridization  of  Vitis  Rotundifolia 


29 


Fig.  76.  Hybrid  (Var.  Winchell  x  V.  Rotundifolia),,  Transverse  Section  of  Bundles 


Hybridization  of  Yitis  Rotundifolia 


30 


Fig.  77.  Hybrid  (Var.  Winchell  x  V.  rotundtfolia)  ,  Transverse  Section  of  Bundi.es. 


Hybridization  of  Yitis  Rotundifolia 


31 


Fig.  78.  Hybrid  (Var.  Winchell  x  V.  Rotundifolia),  Transverse  Section  of 

Internode 


